refactored Decorator pattern

Structural/Decorator/Booking.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+interface Booking
+{
+    public function calculatePrice(): int;
+
+    public function getDescription(): string;
+}

Structural/Decorator/BookingDecorator.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+abstract class BookingDecorator implements Booking
+{
+    /**
+     * @var Booking
+     */
+    protected $booking;
+
+    public function __construct(Booking $booking)
+    {
+        $this->booking = $booking;
+    }
+}

Structural/Decorator/DoubleRoomBooking.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+class DoubleRoomBooking implements Booking
+{
+    public function calculatePrice(): int
+    {
+        return 40;
+    }
+
+    public function getDescription(): string
+    {
+        return 'double room';
+    }
+}

Structural/Decorator/ExtraBed.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+class ExtraBed extends BookingDecorator
+{
+    private const PRICE = 30;
+
+    public function calculatePrice(): int
+    {
+        return $this->booking->calculatePrice() + self::PRICE;
+    }
+
+    public function getDescription(): string
+    {
+        return $this->booking->getDescription() . ' with extra bed';
+    }
+}

Structural/Decorator/JsonRenderer.php

@@ -1,11 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-class JsonRenderer extends RendererDecorator
-{
-    public function renderData(): string
-    {
-        return json_encode($this->wrapped->renderData());
-    }
-}

Structural/Decorator/README.rst

@@ -25,33 +25,33 @@ Code
 
 You can also find this code on `GitHub`_
 
-RenderableInterface.php
+Booking.php
 
-.. literalinclude:: RenderableInterface.php
+.. literalinclude:: Booking.php
    :language: php
    :linenos:
 
-Webservice.php
+BookingDecorator.php
 
-.. literalinclude:: Webservice.php
+.. literalinclude:: BookingDecorator.php
    :language: php
    :linenos:
 
-RendererDecorator.php
+DoubleRoomBooking.php
 
-.. literalinclude:: RendererDecorator.php
+.. literalinclude:: DoubleRoomBooking.php
    :language: php
    :linenos:
 
-XmlRenderer.php
+ExtraBed.php
 
-.. literalinclude:: XmlRenderer.php
+.. literalinclude:: ExtraBed.php
    :language: php
    :linenos:
 
-JsonRenderer.php
+WiFi.php
 
-.. literalinclude:: JsonRenderer.php
+.. literalinclude:: WiFi.php
    :language: php
    :linenos:
 

Structural/Decorator/RenderableInterface.php

@@ -1,8 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-interface RenderableInterface
-{
-    public function renderData(): string;
-}

Structural/Decorator/RendererDecorator.php

@@ -1,24 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-/**
- * the Decorator MUST implement the RenderableInterface contract, this is the key-feature
- * of this design pattern. If not, this is no longer a Decorator but just a dumb
- * wrapper.
- */
-abstract class RendererDecorator implements RenderableInterface
-{
-    /**
-     * @var RenderableInterface
-     */
-    protected $wrapped;
-
-    /**
-     * @param RenderableInterface $renderer
-     */
-    public function __construct(RenderableInterface $renderer)
-    {
-        $this->wrapped = $renderer;
-    }
-}

Structural/Decorator/Tests/DecoratorTest.php

@@ -2,32 +2,37 @@
 
 namespace DesignPatterns\Structural\Decorator\Tests;
 
-use DesignPatterns\Structural\Decorator;
+use DesignPatterns\Structural\Decorator\DoubleRoomBooking;
+use DesignPatterns\Structural\Decorator\ExtraBed;
+use DesignPatterns\Structural\Decorator\WiFi;
 use PHPUnit\Framework\TestCase;
 
 class DecoratorTest extends TestCase
 {
-    /**
-     * @var Decorator\Webservice
-     */
-    private $service;
-
-    protected function setUp()
+    public function testCanCalculatePriceForBasicDoubleRoomBooking()
     {
-        $this->service = new Decorator\Webservice('foobar');
+        $booking = new DoubleRoomBooking();
+
+        $this->assertEquals(40, $booking->calculatePrice());
+        $this->assertEquals('double room', $booking->getDescription());
     }
 
-    public function testJsonDecorator()
+    public function testCanCalculatePriceForDoubleRoomBookingWithWiFi()
     {
-        $service = new Decorator\JsonRenderer($this->service);
+        $booking = new DoubleRoomBooking();
+        $booking = new WiFi($booking);
 
-        $this->assertEquals('"foobar"', $service->renderData());
+        $this->assertEquals(42, $booking->calculatePrice());
+        $this->assertEquals('double room with wifi', $booking->getDescription());
     }
 
-    public function testXmlDecorator()
+    public function testCanCalculatePriceForDoubleRoomBookingWithWiFiAndExtraBed()
     {
-        $service = new Decorator\XmlRenderer($this->service);
+        $booking = new DoubleRoomBooking();
+        $booking = new WiFi($booking);
+        $booking = new ExtraBed($booking);
 
-        $this->assertXmlStringEqualsXmlString('<?xml version="1.0"?><content>foobar</content>', $service->renderData());
+        $this->assertEquals(72, $booking->calculatePrice());
+        $this->assertEquals('double room with wifi with extra bed', $booking->getDescription());
     }
 }

Structural/Decorator/Webservice.php

@@ -1,21 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-class Webservice implements RenderableInterface
-{
-    /**
-     * @var string
-     */
-    private $data;
-
-    public function __construct(string $data)
-    {
-        $this->data = $data;
-    }
-
-    public function renderData(): string
-    {
-        return $this->data;
-    }
-}

Structural/Decorator/WiFi.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+class WiFi extends BookingDecorator
+{
+    private const PRICE = 2;
+
+    public function calculatePrice(): int
+    {
+        return $this->booking->calculatePrice() + self::PRICE;
+    }
+
+    public function getDescription(): string
+    {
+        return $this->booking->getDescription() . ' with wifi';
+    }
+}

Structural/Decorator/XmlRenderer.php

@@ -1,15 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-class XmlRenderer extends RendererDecorator
-{
-    public function renderData(): string
-    {
-        $doc = new \DOMDocument();
-        $data = $this->wrapped->renderData();
-        $doc->appendChild($doc->createElement('content', $data));
-
-        return $doc->saveXML();
-    }
-}